Fluid check valves are known and are commonly used in various types of aircraft fluid control systems such as for the engine bleed air system which supplies pressurized airflow to the cabin and auxiliary systems. The check valves allow the fluid being transported within the piping or ducting system to flow in one direction by opening the check valve. When the fluid starts to reverse flow direction, the check valve closes and thereby prevents the flow from reversing. This feature is especially important in aircraft applications where bleed air from the jet engine compressor is used to supply airflow to the aircraft auxiliary systems should an engine compressor stall occur. Immediately upon the onset of compressor stall, the check valve must close and prevent airflow in an opposite direction from the auxiliary system into the engine compressor. If this does not occur and air is allowed to backflow, re-start of the engine is compromised.
In certain applications, especially in aircraft applications, it is desirable to rotationally index the various system components such as the fluid ducts leading to and from the check valve. Still in some other applications and installations it is also desirable to index or “clock” the clamping band that is used to hold various parts joined to the check valve such as the fluid duct flanges. In some applications, it would also be desirable to prevent the use of a light duty clamping band when a heavy duty clamping band is required.